The present invention relates to a high-security and low-noise agricultural machine.
In particular, by low noise it is meant that the machine of the present invention is configured so as to be able to absorb any misalignment or positioning errors of components engaged with each other that can cause strong increases in noise.
In particular, the terms “agricultural machine” refer to a machine comprising an engine, generally endothermic internal combustion operating on petrol or Diesel cycle, a clutch, a gearbox, an axle fitted with wheels, a handlebar of motorcycle type, often called “handles” provided with the controls necessary for the various drives, and a power take-off to which a tool to be used is connected.
By way of example, if such a tool is a cutter adapted to hoe the soil with motor on the side opposite to the operator, the machine is called “walking tractor”, otherwise, if the tool is a cutting bar with motor on the operator's side, these machines are called “motor mowers”.
Moreover, if the aforesaid handlebar is movable with respect to the power take-off and can rotate up to 180°, allowing the operator to work in a “walking tractor” or “motor mower” configuration, the definition of such machines includes the word “reversible”.
Nowadays, for safety reasons, the regulations in force in numerous markets require that if the operator abandons the grip on the handlebars, the machine has to stop, preferably within a limited period of time.
This result can be obtained thanks to the presence of a “security” lever, placed on the handlebars, which the operator during use of the relative machine must keep pressed to keep the machine in operation.
In fact, this lever is connected to the endothermic engine so that, when released, it causes it to shut down.
However, disadvantageously, the shutdown of the engine in case of release of the aforesaid “security” lever does not occur immediately because of the inertia of the engine and of those of the connected kinematic mechanisms.
A consequence of this fact is that the machine can continue to move for some time even after releasing the handlebars by the driver, thus creating a potentially dangerous situation for the user.
Another limitation of the current solution described above lies in the fact that, after leaving the handlebars, and having therefore begun the shutdown process of the engine, in order to continue the work the operator is forced to restart the shutdown engine.
Since most engines of this type have a manual start, the maneuver is not always easy due to the physical effort required.
This unfortunately may induce some operators to tamper with the safety device, locking it in the actuated position, thereby avoiding the shutdown of the engine to avoid the burden of the subsequent restart, but consequently significantly reducing the safety of the machine.
Another limitation of the configuration currently in use and described above mainly affects the machines provided with gearboxes in oil bath.
In fact, in these particular gear machines, the motion it is transmitted via a mechanically actuated clutch through which the entire available power passes.
In order to contain the track width of the machine, reducing the transverse dimensions and allowing the execution of special cultivation work, the diameter of this clutch is rather reduced in relation to the power to be transmitted.
This limited volume available often makes it mandatory to use dry cone clutches often having a sharp drive, high wear and relevant problems of heat dissipation.
In order to reduce the start-up transients, origin of overheating especially with high inertia tools, very stiff springs are often used today which make a mechanical control of the clutch weary and little ergonomic. Furthermore, the manual actuation of a safety lever directly connected to the clutch itself is tiring and unwieldy, having to be maintained for the duration of the work.
Finally, wear is often premature, requiring frequent adjustments of the control and increasing risk of malfunctions with potential safety risks.